JP2009251354A - Image forming apparatus and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of adjusting image quality accurately after a reposed time and obtaining desired printing quality, by confirming previous print job information every time of returning from a reposed state, and to provide a method for controlling the same. <P>SOLUTION: The image forming apparatus 100 of electrophotographic system having a function of performing adjustment of image quality when performing image formation includes a detection means 110 for detecting a fixing temperature of a fixing apparatus 15; a storage means 120 for storing an application history of a development bias; a count means 130 for counting a reposed time from a point when an operation of image formation is ended; a determination means 140 for determining a change range of the development bias immediately before the end of the operation of image formation; and an execution means 150 for executing adjustment of image quality by setting the development bias based on a determination result from the determination means 140 when the reposed time or the fixing temperature exceeds a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine and a printer, and a method for controlling the image forming apparatus, and more particularly to an image forming apparatus having an image quality adjustment function for stabilizing print image quality and an image The present invention relates to a method for controlling a forming apparatus.

  A conventional electrophotographic image forming apparatus is equipped with a developing device for forming a toner image. This developing apparatus is roughly classified into one using a one-component developing system using one-component toner and one using a two-component developing system using a two-component developer including a non-magnetic toner and a magnetic carrier.

  A developing device using the one-component developing method is suitable for downsizing, but is not suitable for high-speed development. Therefore, in a high-speed and long-life image forming apparatus, a two-component developing method developing device is almost adopted.

  In this type of developing apparatus using a two-component developer, the carrier itself in the two-component developer is not consumed and remains in the apparatus, but does not decrease. However, the toner is consumed and decreased. Therefore, in order to stabilize the image quality, the toner is appropriately replenished so that the toner concentration of the two-component developer is kept constant.

  In addition, since the image quality of the image forming apparatus changes due to the influence of deterioration of the photoconductor and developer and changes in environmental conditions, various image quality adjustment technologies (also known as process control technologies) are used to prevent this phenomenon. Recently, these adjustment modes have been implemented even when the image forming apparatus is not used for a long time.

  As a conventional technique, an image forming apparatus is proposed in which image quality adjustment is performed at the time of returning from the neglected mode. The return from the neglected mode means that the image forming engine has been stopped until then. For example, in the case of the two-component development method, the developer has not been charged for a while, or the machine is installed. The temperature, humidity environment, and the like are changing (for example, the difference in temperature and humidity between morning and noon). When environmental conditions change, it is conceivable that the charge amount of the developer, the potential of the photoreceptor, and the like change. In order to cause a change in the image quality density and a change in color tone after such a change, the image quality adjustment mode is executed to ensure a desired print image quality.

  Actually, in order to obtain the optimum print image quality by adjusting the image density on the high density side or adjusting the halftone density, it takes about 30 to 60 seconds to adjust the image quality. In particular, when a document with a low printing rate is continuously printed, toner replenishment is hardly performed, and the toner charge amount increases. Accordingly, in order to obtain an image density of a certain level or more, the apparatus is operated on the apparatus side so as to increase the developing bias and ensure the effective developing potential (high developing potential).

  However, since the toner charge amount decreases when the apparatus is left unattended, if development is performed in that state, a phenomenon in which an abnormally high (high) image density occurs will be considered. ing.

  Therefore, as a conventional technique, for example, in order to control the maximum image density, a detection means for detecting the amount of toner adhering to a toner image having a substantially maximum image density formed on the photosensitive member, and a developer by rotating the developer A developer conveying body that conveys the toner, and developing means for developing the toner by attaching toner to the electrostatic latent image on the photosensitive member, and a predetermined image density based on information detected by the detecting means An image density adjusting unit that performs adjustment, and the image density adjusting unit performs a first adjustment for changing a reference value of the number of rotations of the developer conveying body in accordance with a history of the developer, and control of the maximum image density. An image forming apparatus is disclosed that is executed at different timings with respect to the developer history with respect to the second adjustment in which the amount of change from the reference value of the developing bias applied when performing the process is changed according to the history of the developer. (Patent) See Document 1).

As another example, in an image forming apparatus that optimizes a density control factor that affects image density, a plurality of processing modes having different numbers of steps are selectively used as a processing mode that optimizes the density control factor. It is configured to be executable, and when returning from sleep, it is determined whether or not a criterion regarding a change in the state of the apparatus is satisfied, and one processing mode is selectively selected from the plurality of processing modes according to the determination result An image forming apparatus is disclosed in Japanese Patent Application Laid-Open No. H10-260260 (see Patent Document 2).
JP 2001-154434 A JP 2003-177638 A

  However, in the above-described conventional technology, there is a problem that the main adjustment may be performed during a print job, and the job efficiency is lowered. Also, in the conventional technique described later, since the optimum processing mode is performed in order to obtain a desired print image quality when returning from the sleep mode, this processing process is required in every return from the sleeve mode. There is a problem of reducing job efficiency.

  The present invention has been made in view of the conventional problems, and an image forming apparatus and an image that can accurately perform image quality adjustment by confirming previous print job information when returning from the neglected state every time. It is an object of the present invention to provide a method for controlling a forming apparatus.

An image forming apparatus and a method for controlling the image forming apparatus according to the present invention for solving the above-described problems are as follows.
The present invention relates to an electrophotographic image forming apparatus having a function of adjusting image quality when image formation is performed, a detection unit that detects a fixing temperature of a fixing unit, a storage unit that stores a development bias application history, Counting means for counting the standing time from the end of the image forming operation, judging means for judging the change width of the developing bias immediately before the end of the image forming operation, and when the leaving time or the fixing temperature exceeds a predetermined value And executing means for setting the developing bias and executing image quality adjustment based on the result of the determining means.

  In the present invention, it is preferable that the execution unit sets an effective development potential based on a result of the determination unit when the standing time or the fixing temperature exceeds a predetermined value.

  In the present invention, it is preferable that the execution unit sets a developing bias based on an average printing rate.

  In the present invention, it is preferable that the determination means determine based on an increase width of the developing bias.

  Further, the present invention preferably includes setting means for setting the length of the standing time or the decrease width of the fixing temperature.

  In the present invention, it is preferable that the setting means is changed with respect to deterioration of the developer.

  The present invention also relates to a method for controlling an electrophotographic image forming apparatus having a function of adjusting image quality when performing image formation, and a detection step for detecting a fixing temperature of a fixing unit and a development bias application history. A storing step for counting, a counting step for counting a leaving time from the end of the image forming operation, a determining step for determining a change width of the developing bias immediately before the end of the image forming operation, and the leaving time or the fixing temperature are predetermined. An execution step of executing an image quality adjustment function based on the result of the determination means when the value is exceeded.

  In the present invention, it is preferable that the effective development potential is set based on a result of the determination step when the leaving time or the fixing temperature exceeds a predetermined value in the execution step.

  In the present invention, it is preferable that the execution step sets a developing bias based on an average printing rate.

  In the present invention, it is preferable that the determination step is determined on the basis of the increase width of the developing bias.

  Further, the present invention preferably includes a setting step for setting the length of the standing time or the decrease width of the fixing temperature.

  In the present invention, it is preferable that the setting step is changed with respect to deterioration of the developer.

  According to the present invention, in an electrophotographic image forming apparatus having a function of adjusting image quality when image formation is performed, a detection unit that detects a fixing temperature of a fixing unit and a storage unit that stores an application history of a developing bias A counting unit that counts a standing time from the end of the image forming operation, a judging unit that determines a change width of the developing bias immediately before the end of the image forming operation, and the standing time or the fixing temperature exceeds a predetermined value. And an execution means for executing the image quality adjustment by setting the developing bias based on the result of the determination means, thereby accurately adjusting the image quality with an appropriate print density after leaving the image forming apparatus. Since it can be carried out, excellent print image quality can always be maintained.

  According to the present invention, the execution unit sets the effective developing potential based on the result of the determination unit when the standing time or the fixing temperature exceeds a predetermined value. The printing density after being left can be made appropriate, and excellent printing image quality can always be maintained.

  Further, according to the present invention, the execution means sets the developing bias based on the average printing rate, so that the printing density after leaving the image forming apparatus can be made appropriate, and always excellent printing can be achieved. Image quality can be maintained.

  In addition, according to the present invention, the determination means determines based on the increase width of the developing bias, and in particular, maintains the print image quality after the return after continuous printing of the low print rate original. Can do.

  In addition, according to the present invention, since the setting means for setting the length of the leaving time or the decrease range of the fixing temperature is provided, the image quality adjustment function can be executed according to the leaving environment, so that the print image quality after returning is maintained. can do.

  Further, according to the present invention, the setting means is changed with respect to the deterioration of the developer, so that it is possible to cope with the use of the image forming apparatus, so that the print image quality after the return is maintained. be able to.

  In addition, according to the present invention, in the control method of an electrophotographic image forming apparatus having a function of adjusting image quality when performing image formation, a detection process for detecting a fixing temperature of a fixing unit and an application history of a developing bias A storing step for storing the image, a counting step for counting a standing time from the end of the image forming operation, a determining step for determining a change width of the developing bias immediately before the end of the image forming operation, and the standing time or fixing temperature. And an execution step of executing an image quality adjustment function based on the result of the determination means when the image quality exceeds a predetermined value, thereby accurately adjusting the image quality with an appropriate print density after leaving the image forming apparatus. Therefore, excellent print image quality can always be maintained.

  In the image forming apparatus according to the present invention, the effective developing potential is set based on a result of the determination step when the standing time or the fixing temperature exceeds a predetermined value. The printing density after being left can be made appropriate, and excellent printing image quality can always be maintained.

  Further, according to the present invention, by setting the developing bias in the execution step based on the average printing rate, the printing density after leaving the image forming apparatus can be made appropriate, and always excellent printing can be performed. Image quality can be maintained.

  In addition, according to the present invention, the determination step is determined based on the increase width of the developing bias, and in particular, the print image quality after returning after the continuous printing of the low print rate original is maintained. Can do.

  In addition, according to the present invention, the image quality adjustment function can be executed according to the leaving environment by providing a setting step for setting the length of the leaving time or the decrease range of the fixing temperature, so that the print image quality after the return is maintained. can do.

  In addition, according to the present invention, since the setting process is changed with respect to the deterioration of the developer, it is possible to cope with the use of the image forming apparatus, so that the print image quality after the return is maintained. be able to.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an electrical configuration for adjusting image quality in the image forming apparatus.

  As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present embodiment is a fixing device (fixing unit) in the electrophotographic image forming apparatus 100 having a function of adjusting image quality when performing image formation. Detection means 110 for detecting a fixing temperature of 15, storage means 120 for storing the application history of the developing bias applied between the photosensitive drum 101 and the developing device 102, and a standing time from the end of the image forming operation. A counting unit 130 for counting, a determining unit 140 for determining a change width of the developing bias immediately before the end of the image forming operation, and a developing bias based on a result of the determining unit 140 when the leaving time or the fixing temperature exceeds a predetermined value. And executing means 150 for executing the image quality adjustment function.

First, the overall configuration of the image forming apparatus 100 will be described.
The image forming apparatus 100 according to the present embodiment forms multi-color and single-color images on a sheet based on read image data of a document or image data transmitted via a network or the like. Therefore, as shown in FIG. 1, the image forming apparatus 100 includes an exposure unit E, a photosensitive drum 101 (101a to 101d), a developing device 102 (102a to 102d), a charging roller 103 (103a to 103d), and a cleaning unit. 104 (104a to 104d), intermediate transfer belt 11, primary transfer roller 13 (13a to 13d), secondary transfer roller 14, fixing device 15, paper transport paths P1, P2, and P3, paper feed cassette 16, and manual paper feed tray 17 and a paper discharge tray 18 and the like.

  The image forming apparatus 100 corresponds to the hues of four colors of cyan (C), magenta (M), and yellow (Y), which are three subtractive primary colors obtained by color separation of black (K) and a color image. Image formation is performed in the image forming units Pa to Pd using the image data.

  The image forming units Pa to Pd have the same configuration. For example, the black image forming unit Pa includes a photosensitive drum 101a, a developing device 102a, a charging roller 103a, a transfer roller 13a, a cleaning unit 104a, and the like. The image forming portions Pa to Pd are arranged in a line in the moving direction (sub-scanning direction) of the intermediate transfer belt 11.

  The charging roller 103 is a contact-type charger that uniformly charges the surface of the photosensitive drum 101 to a predetermined potential. Instead of the charging roller 103, a contact type charger using a charging brush or a non-contact type charger using a charging wire may be used.

  An exposure unit E which is an exposure apparatus of the present invention includes a semiconductor laser, a polygon mirror 4, a first reflection mirror 7, a second reflection mirror 8, and the like (not shown), and images of hues of black, cyan, magenta and yellow. Each of the photosensitive drums 101a to 101d is irradiated with a light beam such as a laser beam modulated by data. On each of the photosensitive drums 101a to 101d, an electrostatic latent image is formed based on image data of each hue of black, cyan, magenta, and yellow.

  The developing device 102 supplies toner to the surface of the photosensitive drum 101 on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. Each of the developing devices 102a to 102d contains toner of each hue of black, cyan, magenta, and yellow, and the electrostatic latent image of each hue formed on each of the photosensitive drums 101a to 101d is black, cyan. Then, the toner images are visualized as magenta and yellow toner images. The cleaning unit 104 removes and collects toner remaining on the surface of the photosensitive drum 101 after development and image transfer.

  The intermediate transfer belt 11 disposed above the photosensitive drum 101 is stretched between the driving roller 11a and the driven roller 11b to form a loop-shaped movement path. The outer peripheral surface of the intermediate transfer belt 11 faces the photosensitive drum 101d, the photosensitive drum 101c, the photosensitive drum 101b, and the photosensitive drum 101a in this order. Primary transfer rollers 13a to 13d are arranged at positions facing the respective photosensitive drums 101a to 101d with the intermediate transfer belt 11 interposed therebetween. Each of the positions where the intermediate transfer belt 11 faces the photosensitive drums 101a to 101d is a primary transfer position. The intermediate transfer belt 11 is formed of a film having a thickness of about 100 to 150 μm.

  The primary transfer rollers 13a to 13d have constant voltage control of a primary transfer bias opposite to the charging polarity of the toner in order to transfer the toner images carried on the surfaces of the photosensitive drums 101a to 101d onto the intermediate transfer belt 11. Applied. As a result, the toner images of each hue formed on the photosensitive drum 101 (101a to 101d) are sequentially transferred to the outer peripheral surface of the intermediate transfer belt 11, and a full color toner image is formed on the outer peripheral surface of the intermediate transfer belt 11. Is done.

  However, when image data of only a part of the hues of yellow, magenta, cyan, and black is input, some of the four photosensitive drums 101a to 101d corresponding to the hue of the input image data. Only the photosensitive member 101 forms an electrostatic latent image and a toner image. For example, when forming a monochrome image, an electrostatic latent image and a toner image are formed only on the photosensitive drum 101 a corresponding to the black hue, and only the black toner image is transferred to the outer peripheral surface of the intermediate transfer belt 11. Is done.

  Each of the primary transfer rollers 13a to 13d is configured by covering the surface of a shaft made of a metal (for example, stainless steel) having a diameter of 8 to 10 mm with a conductive elastic material (for example, EPDM, urethane foam, or the like). A high voltage is uniformly applied to the intermediate transfer belt 11 by the elastic material.

  The toner image transferred to the outer peripheral surface of the intermediate transfer belt 11 at each primary transfer position is conveyed to a secondary transfer position that is a position facing the secondary transfer roller 14 by the rotation of the intermediate transfer belt 11. The secondary transfer roller 14 is pressed against the outer peripheral surface of the intermediate transfer belt 11 whose inner peripheral surface is in contact with the peripheral surface of the driving roller 11a at a predetermined nip pressure during image formation.

  When the paper fed from the paper feed cassette 16 or the manual paper feed tray 17 passes between the secondary transfer roller 14 and the intermediate transfer belt 11, the polarity of the toner charged on the secondary transfer roller 14 is opposite to that of the toner. The high voltage is applied. As a result, the toner image is transferred from the outer peripheral surface of the intermediate transfer belt 11 to the surface of the sheet.

  Of the toner adhering to the intermediate transfer belt 11 from the photosensitive drum 101, the toner remaining on the intermediate transfer belt 11 without being transferred onto the paper is removed by the cleaning unit 12 in order to prevent color mixing in the next process. To be recovered.

  The sheet on which the toner image has been transferred is guided to the fixing device 15, and passes between the heating roller 15a and the pressure roller 15b to be heated and pressurized. As a result, the toner image is firmly fixed on the surface of the paper. The paper on which the toner image is fixed is discharged onto the paper discharge tray 18 by the paper discharge roller 18a.

  In the image forming apparatus 100, a substantially vertical direction for feeding the paper stored in the paper cassette 16 to the paper discharge tray 18 between the secondary transfer roller 14 and the intermediate transfer belt 11 and via the fixing device 15. A paper transport path P1 is provided.

  In the paper transport path P1, a pickup roller 16a that feeds the paper in the paper cassette 16 one by one into the paper transport path P1, a transport roller r that transports the fed paper upward, and the transported paper is predetermined. A registration roller 19 that guides between the secondary transfer roller 14 and the intermediate transfer belt 11 at the timing and a paper discharge roller 18 a that discharges the paper to the paper discharge tray 18 are disposed.

  Further, inside the image forming apparatus 100, a paper conveyance path P2 in which a pickup roller 17a and a conveyance roller r are arranged is formed between the manual paper feed tray 17 and the registration roller 19. Further, a paper transport path P3 is formed between the paper discharge roller 18a and the upstream side of the registration roller 19 in the paper transport path P1.

  The paper discharge roller 18a is rotatable in both forward and reverse directions, and is used for forming a single-sided image for forming an image on one side of a sheet and for forming a second-side image in forming a double-sided image for forming an image on both sides of a sheet. Driven in the forward direction, the paper is discharged to the paper discharge tray 18.

  On the other hand, when the first side image is formed in the double-sided image formation, the discharge roller 18a is driven in the normal rotation direction until the rear end of the paper passes through the fixing device 15, and then reversely rotated with the rear end of the paper sandwiched. Driven in the direction, the sheet is guided into the sheet conveyance path P3. As a result, the paper on which the image is formed on only one side when the double-sided image is formed is guided to the paper transport path P1 with the front and back surfaces and the front and rear ends reversed.

  The registration roller 19 feeds a sheet fed from the sheet cassette 16 or the manual feed tray 17 or conveyed via the sheet conveying path P 3 at a timing synchronized with the rotation of the intermediate transfer belt 11. 14 and the intermediate transfer belt 11. For this reason, the registration roller 19 stops rotating when the operation of the photosensitive drum 101 and the intermediate transfer belt 11 is started, and the sheet fed or conveyed prior to the rotation of the intermediate transfer belt 11 has the front end at the registration roller 19. The movement in the sheet conveyance path P1 is stopped in a state where the sheet 19 is in contact with the sheet 19. Thereafter, the registration roller 19 is a position where the secondary transfer roller 14 and the intermediate transfer belt 11 are in pressure contact with each other, at a timing when the front end portion of the sheet and the front end portion of the toner image formed on the intermediate transfer belt 11 face each other. Start spinning.

  At the time of full color image formation in which image formation is performed in all of the image forming portions Pa to Pd, the primary transfer rollers 13a to 13d press the intermediate transfer belt 11 against all of the photosensitive drums 101a to 101d. On the other hand, at the time of monochrome image formation in which image formation is performed only in the image forming portion Pa, only the primary transfer roller 13a is brought into pressure contact with the photosensitive drum 101a.

  Next, an electrical configuration for performing characteristic image adjustment in the image forming apparatus 100 according to the present embodiment will be described.

  As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a detection unit 110 that detects a fixing temperature of the fixing device (fixing unit) 15 and a storage unit that stores a development bias application history of the developing device 102. 120, a counting unit 130 that counts a standing time from the end of the image forming operation, a determination unit 140 that determines a change width of the developing bias immediately before the end of the image forming operation, and a standing time or a fixing temperature is a predetermined value. And an execution unit 150 that sets the developing bias based on the result of the determination unit 140 and executes the image quality adjustment function.

  The execution unit 150 has a function of setting an effective development potential based on the result of the determination unit 140 when the leaving time or the fixing temperature after the image forming operation of the image forming apparatus 100 is over a predetermined value. And a function of setting a developing bias based on the average printing rate.

  The determination unit 140 has a function of determining based on the increase width of the developing bias of the developing device 102.

Here, operation control of the image forming apparatus 100 according to the present embodiment will be described based on a flowchart.
FIG. 3 is a flowchart showing image adjustment control in image formation of the image forming apparatus according to the present embodiment.

  First, when the image forming apparatus 100 is started and image formation is requested by a user's instruction, a normal print job command is started (step S1) as shown in FIG. It is determined whether or not it has elapsed (step S2).

  Specifically, in step S <b> 2, it is determined whether or not the leaving time that the image forming apparatus 100 has been left without being operated has been left for a predetermined time (for example, 1 hour) or longer.

  If it is determined in step S2 that the leaving time is short (not so much left), the print job is started as it is (step S5).

  On the other hand, if it is determined in step S2 that the standing time has been left for more than 1 hour (the standing time is long), the developing bias after a certain period of time before being left, for example, after 10 minutes, suddenly changes. Whether or not there is is determined (step S3).

  The sudden change in the developing bias is caused by continuous printing of the low-printing rate document as described above. Therefore, the developing bias changes from the history of the developing bias stored in the storage unit 120 by the determination unit 140 in step S3. Whether the width is changed to a developing bias of 100 V or more in which a large change in image density appears is determined.

  In step S3, if the determination unit 140 determines that there is no sudden change in the developing bias, the print job is started as it is (step S5).

  On the other hand, if it is determined in step S3 that the developing means 140 has caused a sudden change in the developing bias, the process proceeds to step S4, and preset image quality adjustment (process control) is performed.

  In this way, it is possible to suppress a rapid increase in the print image density after the image forming apparatus 100 is left unattended.

Next, as a modification of the present embodiment, operation control in image formation when the fixing temperature is considered in image adjustment in the image forming apparatus 100 according to the present embodiment will be described.
FIG. 4 is a block diagram showing an electrical configuration for image quality adjustment in a modification of the image forming apparatus according to the present embodiment, and FIG. 5 is a flowchart showing image adjustment control in the modification.

  As shown in FIG. 4, the modification stores the electrical configuration of the image forming apparatus 100 described above, that is, the detection unit 110 that detects the fixing temperature of the fixing device 15 and the development bias application history of the developing device 102. The storage unit 120, the counting unit 130 that counts the leaving time from the end of the image forming operation, the determining unit 140 that determines the change width of the developing bias immediately before the end of the image forming operation, and the leaving time or fixing temperature are When the predetermined value is exceeded, the execution unit 150 that executes the image quality adjustment function by setting the development bias based on the result of the determination unit 140 is used. Is provided with setting means 160 for setting the length of the image or the decrease in the fixing temperature of the fixing device 15. The setting unit 160 has a function of changing with respect to the deterioration of the developer.

Hereinafter, operation control of the image forming apparatus 100 according to the modification will be described with reference to a flowchart.
As shown in FIG. 5, the operation in the modified example is performed in the same manner as the image forming apparatus 100 according to the above-described embodiment up to step S2 (see FIG. 3), but in the flow in the modified example, the fixing device 15 is simultaneously performed. The operation control is performed based on the fixing temperature.

  This is because, depending on the operation state of the image forming apparatus 100, the fixing temperature of the fixing apparatus 15 may be lowered depending on the use status of the previous job even if the image forming apparatus 100 is left unused.

  Therefore, when the print job command is started (step S1), if it is determined in step S2 that the leaving time is short (not so much left), the process proceeds to step S6, and the fixing temperature in the fixing device 15 is set. It is determined whether or not the temperature is a predetermined temperature, for example, 60 ° C. or lower.

  If it is determined in step S6 that the fixing temperature is not below 60 ° C., the print job is started as it is (step S5).

  On the other hand, if it is determined in step S6 that the fixing temperature is 60 ° C. or lower, for example, a fixing heater (not shown) provided in the fixing device 15 is turned on and the fixing temperature is increased (step S7). ). Since this up operation is short in the time for which it is left, it is immediately recovered to the target fixing temperature, and thereafter, the process proceeds to step 3 and the operation is performed in the same manner as the image forming apparatus 100 according to the above-described embodiment.

  In this way, it is possible to suppress a rapid increase in the print image density after the image forming apparatus 100 is left unattended.

  In the image forming apparatus 100 using a two-component developer, the developer is deteriorated as the image is output. As the developer deteriorates, the chargeability of the toner decreases.

  Therefore, as shown in FIG. 6, it is possible to adjust the image quality more frequently by shortening the predetermined value of the leaving time according to the life of the developer.

  For example, as shown in FIG. 6, the relationship between the lifetime of the developer and the standing time is converted into the number of image outputs by the recording medium as shown in FIG. 60 minutes, over 10,000 sheets up to 20,000 sheets 65 minutes, over 20,000 sheets up to 30,000 sheets 70 minutes, over 30,000 sheets up to 40,000 sheets 80 minutes 40,000 Over 90 sheets, up to 50,000 sheets is 90 minutes, and over 50,000 sheets is 100 minutes.

  In this way, by setting the predetermined value of the standing time according to the life of the developer, it is possible to always maintain high image quality throughout the life of the developer.

  With the above-described configuration, according to the present embodiment, when the operation operation is started in the image forming apparatus 100, the previous print job information is confirmed at the time of returning from the left state every time, thereby accurately adjusting the image quality. Can be implemented. As a result, it is possible to always output an image with good image quality by accurate image quality adjustment.

  Note that the present invention is not limited to the image forming apparatus and the copying machine having the above-described configuration as long as the image forming apparatus has a function of adjusting image quality when performing image formation. It can be deployed on devices.

  For example, as an operation control of the image forming apparatus, the present invention can be applied to an image forming apparatus having a function of displaying a warning. According to this image forming apparatus, when the change width of the development bias exceeds a predetermined value in the image quality adjustment from the neglected state, if the increase width of the development bias has changed extremely, "The image quality is being adjusted. Please wait for a while."

  Accordingly, it is possible to announce the operating state of the apparatus to the user including determination as to whether or not the image forming apparatus itself is in trouble.

  As another example, the image forming apparatus may be provided with a changeover switch that can switch ON / OFF operation of an execution unit that executes image quality adjustment.

  With this configuration, for users who need urgency and want to print in a short time, the image quality adjustment in this embodiment can be prevented from being performed, so that two types of use are possible. Become.

  As described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a block diagram illustrating an electrical configuration for performing image quality adjustment in the image forming apparatus. FIG. 3 is a flowchart illustrating image adjustment control in image formation of the image forming apparatus. FIG. 9 is a block diagram illustrating an electrical configuration for performing image quality adjustment in a modified example of the image forming apparatus. It is a flowchart which shows the control of the image adjustment in the said modification. FIG. 6 is an explanatory diagram showing a relationship between a developer life and a set value of a standing time.

Explanation of symbols

11 Intermediate Transfer Belt 15 Fixing Device 100 Image Forming Device 101 Photosensitive Drum 102 Developing Device 103 Charging Roller 104 Cleaning Unit 110 Detection Unit 120 Storage Unit 130 Counting Unit 140 Determination Unit 150 Execution Unit 160 Setting Unit

Claims (12)

In an electrophotographic image forming apparatus having a function of adjusting image quality when performing image formation,
Detection means for detecting the fixing temperature of the fixing unit;
Storage means for storing a development bias application history;
A counting means for counting the time left after the image forming operation is completed;
Determining means for determining a change width of the developing bias immediately before the end of the image forming operation;
Execution means for setting the development bias and executing image quality adjustment based on the result of the determination means when the standing time or the fixing temperature exceeds a predetermined value;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the execution unit sets an effective development potential based on a result of the determination unit when the standing time or the fixing temperature exceeds a predetermined value.   The image forming apparatus according to claim 1, wherein the execution unit sets a developing bias based on an average printing rate.   The image forming apparatus according to claim 1, wherein the determination unit makes a determination based on an increase width of the developing bias.   5. The image forming apparatus according to claim 1, further comprising a setting unit configured to set a length of the standing time or a decrease range of the fixing temperature.   The image forming apparatus according to claim 5, wherein the setting unit is changed with respect to deterioration of the developer. In a control method of an electrophotographic image forming apparatus having a function of adjusting image quality when performing image formation,
A detection process for detecting the fixing temperature of the fixing unit;
A storage step of storing a development bias application history;
A counting step for counting the time left after the image forming operation is completed;
A determination step of determining a change width of the developing bias immediately before the end of the image forming operation;
An execution step of executing an image quality adjustment function based on a result of the determination unit when the standing time or the fixing temperature exceeds a predetermined value;
An image forming apparatus control method comprising:   8. The method of controlling an image forming apparatus according to claim 7, wherein the execution step sets an effective developing potential based on a result of the determination step when the standing time or the fixing temperature exceeds a predetermined value. .   The image forming apparatus control method according to claim 7, wherein the execution step sets a developing bias based on an average printing rate.   The method of controlling an image forming apparatus according to claim 7, wherein the determination step determines based on an increase width of the developing bias.   The method for controlling an image forming apparatus according to claim 7, further comprising a setting step of setting a length of the standing time or a decrease width of the fixing temperature.   12. The method of controlling the image forming apparatus according to claim 11, wherein the setting step is changed with respect to deterioration of the developer.

Images